/*********************************************************************
 * Copyright (C) 2007 Andrew Khan
 * <p>
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * <p>
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * <p>
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ***************************************************************************/

package jxl.write.biff;

import jxl.common.Logger;

import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.io.RandomAccessFile;

/**
 * Used to generate the excel biff data using a temporary file.  This
 * class wraps a RandomAccessFile
 */
class FileDataOutput implements ExcelDataOutput {
    // The logger
    private static Logger logger = Logger.getLogger(FileDataOutput.class);

    /**
     * The temporary file
     */
    private File temporaryFile;

    /**
     * The excel data
     */
    private RandomAccessFile data;

    /**
     * Constructor
     *
     * @param tmpdir the temporary directory used to write files.  If this is
     *               NULL then the sytem temporary directory will be used
     */
    public FileDataOutput(File tmpdir) throws IOException {
        temporaryFile = File.createTempFile("jxl", ".tmp", tmpdir);
        temporaryFile.deleteOnExit();
        data = new RandomAccessFile(temporaryFile, "rw");
    }

    /**
     * Writes the bytes to the end of the array, growing the array
     * as needs dictate
     *
     * @param d the data to write to the end of the array
     */
    public void write(byte[] bytes) throws IOException {
        data.write(bytes);
    }

    /**
     * Gets the current position within the file
     *
     * @return the position within the file
     */
    public int getPosition() throws IOException {
        // As all excel data structures are four bytes anyway, it's ok to
        // truncate the long to an int
        return (int) data.getFilePointer();
    }

    /**
     * Sets the data at the specified position to the contents of the array
     *
     * @param pos the position to alter
     * @param newdata the data to modify
     */
    public void setData(byte[] newdata, int pos) throws IOException {
        long curpos = data.getFilePointer();
        data.seek(pos);
        data.write(newdata);
        data.seek(curpos);
    }

    /**
     * Writes the data to the output stream
     */
    public void writeData(OutputStream out) throws IOException {
        byte[] buffer = new byte[1024];
        int length = 0;
        data.seek(0);
        while ((length = data.read(buffer)) != -1) {
            out.write(buffer, 0, length);
        }
    }

    /**
     * Called when the final compound file has been written
     */
    public void close() throws IOException {
        data.close();

        // Explicitly delete the temporary file, since sometimes it is the case
        // that a single process may be generating multiple different excel files
        temporaryFile.delete();
    }
}
